Liquid Formualations Flashcards
What is a liquid formulation?
A homogenous one-phase system that contains the drug and the solvent
How does low pH enhance solubility of a drug? (i.e. which form of drug dominates) Additionally what happens to the total solubility if a co-solvent is added
In Acidic Conditions (low pH) there is a higher conc. of protons - equilibrium shifts to the left - unionised form dominates
–> unionised forms have a greater ability to dissolve in non-polar solvents
- S(total) increases if alcohol Is added in this pH range
How does intermediate pH affectt solubility of drug?
solubility values of both the ionised and unionised forms are comparable as the pH approaches the drugs pKa
How does high pH enhance solubility of drug (i.e. which form of drug dominates) Additionally what happens to the total solubility if a co-solvent is added.
- IONISED FORM dominates
- S(total) decreases if alcohol is added
What does inclusion of a co-solvent do?
It increases the solubility of the UNIONISED FORM
Co-solvency affects the solubility of a drug. Define co-solvency.
A phenomenon where a co-solvent which is non-polar in nature is added to a primary solvent such as water to simply improve the solubility of a particular drug
Give 2 specific examples of co-solvency
- Propylene glycol (co-solvent) dissolves co-trimoxazole in water
- Alcohol and syrup dissolves paracetamol in elixir
Define dialectric constant of a solvent?
- inputted in ED discussion - still waiting for answer
Does inclusion of a co-solvent increase or decrease DC
DECREASES!
Does inclusion of water increase or decrease DC
INCREASES!
How does micellar solubilisation affect solubiity of a drug
Micelles are made up of surfactants
When surfactant concentration is sufficiently high micelles are formed allowing drugs to be solubilised.
When it is low - they orientate towards the air-liquid interface
What assumptions can we make if the solution is CLEAR?
All the drug has be dissolved and so the concentration of SURFACTANTS was optimal
list 2 examples of surfactants and the types of drugs they dissolve
Polysorbates for fat-soluble vitamines and cetamacrogol for griseofulvin
Outline the process of complexation to increase solubility
A drug [D] forms a complex [DC] with a complexing agent [C].
List an example of a complexing agent and its type and 2 drugs that fits into it
Cyclodextrins:
There are 3 types - alpha, beta and gamma cyclodextrins which consists of 6, 7 and 8 units of glucose
DRUG NAME: mefenamic acid and meclofenamic acid
List the basic steps in which liquid medications are made
List 2 considerations
- API and additives solubilised in water
- Flitration
- Filling into containers
- Raw materials must meet requirements on microbial content
- Water must meet the regulatory requirement for purified water
Function of preservatives?
If a microorganism randomly emerges in solution it inhibits its growth by killing It which in turn prevents spoilage and extends shelf life
List a few examples of liquid preparations
- Elixirs
- Mixtures (either solution or suspension)
- Linctus’s
- Lotions
- Liniments
- Paints
- Eye drops
- Ear drops
Define patient-centred care
Health services are tailored to people’s needs and provided in partnership with them. It also involves people, family and communities being respected, informed, engaged and adequately supported
Define biomedical model of healthcare. Which diseases does it treat?
- Most dominant form of model in healthcare practise
- informs that a physical or mental illness in a person has a ‘cause’ which can be cured through treatment
1. Identification of pathogenic stimulus
2. Treatment
3. Physiological changes
4. recovery, chronicity or death
Focuses on treating infectious diseases (e.g. influenza)
Define biopschosocial model of healthcare
Outline the 3 factors and what diseases does it treat
Illness can be caused, treated, prevented by a combination of biological, psychological and social factors
1. Biological: genes
2. Psychological: beliefs, intelligence, mental health issues
3. Social: Education, financial stability, family support, access to healthcare services, public exercise equipment
Focuses on treating NCD’s (e.g. CVD, asthma and diabetes)
Define open-ended questions
Allows the patient to provide a free-form long answer rather than a simple yes or no.
Should avoid ‘WHY’ questions
Define close-ended questions
Directs a person to simply say a ‘yes’ or a ‘no
Describe the elements involved in active listening
- Taking quick notes while patient is talking about their situation
- Double-check the information to reduce misunderstanding by repeating the information
- Qualify the situation with questions
- involves open body language and acknowledgement of concerns.
Define empathy
Involves a non-judgemental and non-evaluative attitude towards the experience of others and acknowledgeing concerns (e.g I completely understand your frustration and I really appreciate your patience right now, thats ok we are all so busy these days)
Surfactants of what HLB value are identified as a useful solubilising agnet
more than or equal to 15
Whats one drawback of the beta-cyclodextrin
It is nephrotoxic
Why do liquid formulations need to maintain a proper level of viscosity?
List 2 examples of viscosity enhancers
to enhancing pouring properties and palatability
- PVP
- Cellulose
Why is density important and provide examples?
To avoid rise or fall in the cerebrospinal fluid
- dextrose
Why is tonocity important and provide examples?
- To avoid pain or irritation
- NaCI
- Mannitol
